Fiber optic cables are widely used to transmit light signals for high speed data transmission. A fiber optic cable typically includes: (1) an optical fiber or optical fibers; (2) a buffer or buffers that surrounds the fiber or fibers; (3) a strength layer that surrounds the buffer or buffers; and (4) an outer jacket. Optical fibers function to carry optical signals. A typical optical fiber includes an inner core surrounded by a cladding that is covered by a coating. Buffers (e.g., loose or tight buffer tubes) typically function to surround and protect coated optical fibers. Strength layers add mechanical strength to fiber optic cables to protect the internal optical fibers against stresses applied to the cables during installation and thereafter. Example strength layers include aramid yarn, steel and epoxy reinforced glass roving. Outer jackets provide protection against damage caused by crushing, abrasions, and other physical damage. Outer jackets also provide protection against chemical damage (e.g., ozone, alkali, acids).
Fiber optic cable connection systems are used to facilitate connecting and disconnecting fiber optic cables in the field without requiring a splice. A typical fiber optic cable connection system for interconnecting two fiber optic cables includes fiber optic connectors mounted at the ends of the fiber optic cables, and an adapter for mechanically and optically coupling the fiber optic connectors together. Fiber optic connectors generally include ferrules that support the ends of the optical fibers of the fiber optic cables. The end faces of the ferrules are typically polished and are often angled. The adapter includes co-axially aligned ports (i.e., receptacles) for receiving the fiber optic connectors desired to be interconnected. The adapter includes an internal split sleeve that receives and aligns the ferrules of the fiber optic connectors when the connectors are inserted within the ports of the adapter. With the ferrules and their associated fibers aligned within the sleeve of the adapter, a fiber optic signal can pass from one fiber to the next. The adapter also typically has a mechanical fastening arrangement (e.g., a snap-fit arrangement) for mechanically retaining the fiber optic connectors within the adapter.
Certain fiber optic cable connection systems can be “ruggedized” or “hardened.” The terms “ruggedized” or “hardened” apply to systems that are robust and suitable for use in an outside environment. An example of an existing ruggedized fiber optic connection system is described in U.S. Pat. Nos. 6,579,014, 6,648,520, and 6,899,467.
Ruggedized fiber optic cable connection systems can include fiber optic adapters that are mounted to outside fiber optic enclosures such as drop terminals, network interface devices, splice enclosures or other housings/enclosures. FIG. 1 shows a fiber optic drop terminal 210 including a front face at which a plurality of ruggedized fiber optic adapters 214 are mounted. The ruggedized fiber optic adapters 214 include inner ports configured to receive non-ruggedized fiber optic connectors and outer ports 216 configured to receive ruggedized fiber optic connectors 322. The inner ports are accessible from inside the drop terminal 210 and the outer ports 216 are accessible from outside the drop terminal 210. Further details regarding drop terminals and their applications in fiber optic networks are disclosed at U.S. Pat. No. 7,292,763 and U.S. Pat. No. 7,489,849, that are hereby incorporated by reference in their entireties.
FIG. 2 illustrates one of the fiber optic adapters 214 in isolation from the drop terminal 210. The fiber optic adapter 214 includes a ruggedized housing 240 having a first piece 242 that defines the inner port 218 of the fiber optic adapter 214 and a second piece 244 that defines the outer port 216 of the fiber optic adapter 214. The first and second pieces 242, 244 can be interconnected by a snap-fit connection to form the ruggedized housing 240. An interior adapter housing 246 mounts inside the ruggedized housing 240. Springs 248 bias the interior adapter housing 246 toward the outer port 216 and allow the interior adapter housing 246 to float within the interior of the ruggedized housing 240. As shown at FIG. 3, the interior adapter housing 246 includes a cylindrical split sleeve holder 251 that houses a standard split sleeve 250. The split sleeve 250 is coaxially aligned with a center axis 252 of the fiber optic adapter 214. The split sleeve 250 includes an inner end 254 that faces toward the inner port 218 of the fiber optic adapter 214 and an outer end 256 that faces toward the outer port 216 of the fiber optic adapter 214. The fiber optic adapter 214 defines a plurality of internal threads 272 within the outer port 216 for use in securing a ruggedized fiber optic connector within the outer port 216. The fiber optic adapter 214 also includes resilient latches 273 for retaining a non-ruggedized fiber optic connector (e.g., a standard SC connector) within the inner port 218. The latches 273 are located adjacent the inner port 218. The interior adapter housing 246 also defines a keying slot 247 adjacent the inner port 218 for ensuring that the non-ruggedized fiber optic connector is inserted into the inner port 218 at the proper rotational orientation. Resilient latches are not provided at the outer port 216. A dust plug 270 is mounted within the outer port 216 of the fiber optic adapter 214 to prevent the adapter from being contaminated when no connector is inserted in the outer port 216.
FIG. 4 illustrates one of the ruggedized fiber optic connectors 322 adapted to be inserted in the outer port 216 of the fiber optic adapter 214. The fiber optic adapter 322 includes an outer housing 328 and a connector body 330. The connector body 330 supports a ferrule 332 located at a connector interface end 326 of the fiber optic connector 322. The outer housing 328 of the fiber optic connector 322 is elongated along a central axis 340 and includes a first end 342 positioned opposite from a second end 344. The first end 342 of the outer housing 328 is positioned at the connector interface end 326 of the fiber optic connector 322 and includes a pair of opposing extensions or paddles 346 positioned on opposite sides of the connector interface housing 330. The paddles 346 are generally parallel to the central axis 340 and are separated from one another by a gap 348 in which the connector body 330 is located. The paddles 346 have different shapes and mate with corresponding regions of the outer port 216 to provide a keying function for ensuring that the fiber optic connector 322 is mounted at the proper rotational orientation within the outer port 216. The second end 344 of the outer housing 328 is adapted to receive a fiber optic cable 350 having a fiber 353 that terminates in the ferrule 332. A resilient boot 352 can be positioned over the second end 344 of the outer housing 328 to provide bend radius protection at the interface between the outer housing 328 and the fiber optic cable 350.
Referring still to FIG. 4, the fiber optic connector 322 also includes a retention nut 358 rotatably mounted about the exterior of the outer housing 328. The retention nut 358 is free to be manually turned relative to the outer housing 328 about the central axis 340. The retention nut 358 includes an externally threaded portion 362 and a gripping portion 364. The gripping portion 364 includes a plurality of flats that allow the gripping portion 364 to be easily grasped to facilitate manually turning the retention nut 358 about the central axis 340. To secure the fiber optic connector 322 within the outer port 216 of the fiber optic adapter 214, the threaded portion 362 is threaded into the inner threads 272. When the fiber optic connector 322 is secured within the outer port, the ferrule 332 fits within the outer end 256 of the split sleeve 250 of the fiber optic adapter 214.
FIGS. 5 through 8 show a standard non-ruggedized SC fiber optic connector 422 adapted to be inserted in the inner port 218 of the fiber optic adapter 214. The connector 422 includes a connector body 424 in which a ferrule assembly is mounted. The connector body 424 includes a first end 426 positioned opposite from a second end 428. The first end 426 provides a connector interface at which a ferrule 430 of the ferrule assembly is supported. Adjacent the first end 426, the connector body 424 includes retention shoulders 432 that are engaged by the resilient latches 273 of the adapter 214 when the connector 422 is inserted in the inner port 218. The latches 273 function to retain the connector 422 within the inner port 218. The second end 428 of the connector body 424 is adapted to receive a fiber optic cable 450 having a fiber 453 that terminates in the ferrule 430. A resilient boot 452 can be positioned at the second end 428 of the connector body 424 to provide bend radius protection at the interface between the connector body 424 and the fiber optic cable 450.
The connector 422 also includes a retractable release sleeve 434 that mounts over the connector body 424. The release sleeve 434 can be slid back and forth relative to the connector body 424 through a limited range of movement that extends in a direction along a longitudinal axis 454 of the connector 422. The release sleeve 434 includes release ramps 436 that are used to disengage the latches 273 from the retention shoulders 432 when it is desired to remove the connector 422 from the inner port 218. For example, by pulling back (i.e., in a direction toward the second end 428 of the connector body 424) on the retention sleeve 434 while the connector 422 is mounted in the inner port 218, the release ramps 436 force the latches 273 apart from one another a sufficient distance to disengage the latches 273 from the retention shoulders 432 so that the connector 422 can be removed from the inner port 218. The release sleeve 434 includes a keying rail 435 that fits within the keying slot 247 of the interior adapter housing 246 to ensure proper rotational alignment of the connector 422 within the inner port 218. When the connector 422 is latched within the inner port 218, the ferrule 430 fits within the inner end 254 of the split sleeve 250 of the fiber optic adapter 214. Further details regarding SC type fiber optic connectors are disclosed at U.S. Pat. No. 5,317,663, that is hereby incorporated by reference in its entirety.
For some applications, there exists a desire to insert non-ruggedized connectors into ruggedized adapter ports. A prior art technique for accommodating this need involves removing the interior adapter housing 246 from the ruggedized housing 240 and replacing the interior adapter housing 246 with a standard SC adapter housing (e.g., see U.S. Pat. No. 5,317,663, that was previously incorporated by reference in its entirety). The standard SC adapter housing is secured within the ruggedized housing 240 with a potting material. However, this process is time consuming and requires the fiber optic adapter 214 to be disassembled. There is a need for improved techniques for providing compatibility between ruggedized and non-ruggedized fiber optic components.